1. Field of the Invention
The present invention relates to an image capturing device to be mounted on a recording apparatus, such as an inkjet printer, and a recording apparatus including the image capturing device.
2. Description of the Related Art
A typical inkjet recording apparatus ejects ink from a recording head mounted on a carriage while the carriage is reciprocating in the main-scanning direction (direction in which the carriage moves) to cause the ink to stick to a recording medium placed on a supporting plate, thereby recording an image (dots) on the recording medium. The recording apparatus conveys the recording medium in the sub-scanning direction (direction perpendicular to the direction in which the carriage moves) by using a conveying roller or the like and repeatedly performs the recording in the main-scanning direction, thereby forming an image on the recording medium. The supporting plate supports the recording medium while the ink is ejected onto the recording medium.
In the inkjet recording apparatus described above, amounts of ink ejected from the recording heads varies depending on a nozzle condition of the recording heads, fluctuation of viscosities of the ink, variability of piezoelectric elements to be driven for the ejection, and the like. Accordingly, color reproduction of an image to be formed with the ink ejected from the recording heads can disadvantageously vary. While ink ejection amounts of a single apparatus can change with time, ink ejection amounts can vary on an apparatus-by-apparatus basis. Accordingly, also with such a variation, color reproduction of an image to be formed with ink ejected from the recording heads can disadvantageously vary.
In view of these circumstances, some types of the inkjet recording apparatus described above perform control, for example, as follows. A test pattern, which is an object, is formed on a recording medium. Depending on the result of color measurement on the test pattern by using a colorimeter, an amount of ink ejected from recording heads is corrected so that colors of an image to be formed with ink ejected from the recording heads are reproduced without a variance.
Examples of the colorimeter described above include a colorimeter that performs color measurement by using a spectrometer and a colorimeter that performs color measurement by receiving light reflected from the test pattern. Use of a spectrometer improves accuracy in color measurement at the expense of an increase in cost because a spectrometer is relatively expensive. A colorimeter using reflected light is relatively inexpensive with the disadvantage of rather low accuracy in color measurement due to the variance of the reflected light according to an environmental condition.
Therefore, there is a need for developing equipment that is relatively inexpensive and performs very accurate color measurement.
Technical documents applied prior to the present invention include Japanese Patent No. 3129502, in which a technique for increasing accuracy in color measurement by capturing an image of a reference color chart and an image of an object including an object simultaneously or separately to obtain RGB data pertaining to the reference color chart and the object, and correcting the RGB data pertaining to the object based on the RGB data pertaining to the reference color chart is disclosed.
Also disclosed in Japanese Patent No. 3129502 is an aspect that the image of the reference color chart and the image of the object including the object are captured simultaneously to correct the RGB data pertaining to the object.
However, the technique disclosed in Japanese Patent No. 3129502 is based on an assumption that image capturing is performed in a state where an image capturing device and the object are placed at fixed positions. Accordingly, the technique is substantially inapplicable to a case where the image capturing device is to be moved.